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3 years ago

15

Traffic along a stretch of road moves at an average speed that varies inversely with the number of cars on it. When there are 15

00 cars, the average speed is 45 mi/h. What is the average speed when there are 1800 cars?

1 answer:

RSB [31]3 years ago

7 0

Answer:

37.5 miles per hour

Step-by-step explanation:

The traffic along a stretch road moves at an average speed that carried inversely as the number of cars

Average speed= k/number of cars.

When there are 1,500 cars the average speed is 45

The first step is to calculate the constant k

45= k/1500

k = 1,500 × 45

k= 67,500

Therefore the average speed when there are 1,800 cars can be calculated as follows

Average speed= 67,500/1,800

= 37.5 miles per hour

Hence the average speed is 37.5 moles per hour

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A pond has 150 fish and the population decreases by 8% each day. How many days before there are 30 fish

nlexa [21]

Answer:

19 days

Step-by-step explanation:

Given

$a = 150$ --- initial

$r = 8\%$ -- rate

Required

Days when the fish gets to 30

The function is exponential and as such it follows;

$y = ab^x$

Where x represents the number of days and y the number of fishes

Because the fishes decreases;

$b = 1 - r$

So, we have:

$b = 1 - 8\%$

Express as decimal

$b = 1 - 0.08$

$b = 0.92$

In $y = ab^x$

$a =150$

$y = 30$

$b = 0.92$

So, we have:

$30 = 150 * 0.92^x$

Divide both sides by 150

$0.2 = 0.92^x$

Take log of both sides

$log(0.2) = log(0.92^x)$

Apply law of logarithm

$log(0.2) = x\ log(0.92)$

Make x the subject

$x = \frac{log(0.2)}{log(0.92)}$

$x = \frac{-0.6990}{-0.0362}$

$x = 19.309$

$x \approx 19$

<em>Hence, it takes approximately 19 days</em>

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2 years ago

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Scilla [17]

Answer:

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Step-by-step explanation:

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x= $\sqrt{784-576}$

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Answer:

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galben [10]

Answer:

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Step-by-step explanation:

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